Overdriving the transfer case?

Diffs, axles, lockers, transmissions, portals, that kind of thing.
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kdiqq
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Overdriving the transfer case?

Post by kdiqq »

I know this may seem odd, but I have been trying to think of different ways to 'add overdrive' to the Pinz.

After investigating the transmission and the direct drive of the 5th gear, it didn't look like a regear of 5th was possible. It has been discussed that you can regear 4th to be OD and shift 1-2-3-5-4, but that seemed impractical to me. After looking at the t-case specs, it looks like the 710 already has a slightly overdriven t-case. Has anyone explored regearing the hi-range to go from a 0.88 to something like a 0.70? It looks like it may be a very easy way to get the crawler 5 speed working like an overdriven 5 speed while still being able to crush offroad like nothing has been changed!

If doable, I can absolutely get several sets made once I pick a an acceptable ratio. Pinz has to be able to do at least 120mph ;) Not really, but 80mph theoretical would make 65mph much more economical!
1977 Austrian 710M
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Garrycol
Australia
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Re: Overdriving the transfer case?

Post by Garrycol »

There was a thread some months back about someone putting an overdrive in a Pinz - a search may find it for you.

Garry
1973 Haflinger AP700
1977 Landrover FC 101
2007 Range Rover Sport TDV6
1971 Jaguar Series 3 E-Type Conv
1957 Landrover 88" Station Wagon
1957 Landrover 88"
kdiqq
United States of America
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Location: Houston, TX

Re: Overdriving the transfer case?

Post by kdiqq »

I saw the thread on adding an overdrive unit and of those who overdrove 4th gear. Neither of those appeal to me because it either adds another point of failure or affects it's operation offroad. After looking at some pictures of a t-case all torn down, it looks very doable! My only concern is having enough meat on the gear. I'd absolutely down to guinea pig this! Even more exciting, it should allow the speedo to function the same! (I think, maybe)
1977 Austrian 710M
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Garrycol
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Re: Overdriving the transfer case?

Post by Garrycol »

Different vehicle - but I have had a bolt on overdrive to the transfer case of my Landrover FC 101 for over 6 years and it has never caused an issue - I just carry the original bits in my spares so that if it does play up I can take it out by the roadside. I have just covered 3000km in a week travelling where O/d was in and it ran fine.

However what you are proposing with the hi range gear in the Pinz transfer case should be doable - again with the tfr case in my 101 various hi range gear ratios are available off the shelf (surely the Pinz would be the same). The hi range gear ratio in my 101 is 1.03 but ratios from .996 through to 1.3 are available and I have the .996 overdrive ratios to go in when I have a chance and they can be changed with the box in the vehicle.

So if you can get different gears it should work - however remember by doing what you propose you will be raising the overall gearing in hi range so you need to ensure your relative low torque engine can pull you in 1st up a hill. That is the beauty of a separate overdrive unit that was the subject of the thread I mentioned that basic gearing remains unchanged when O/d is out.

Garry
1973 Haflinger AP700
1977 Landrover FC 101
2007 Range Rover Sport TDV6
1971 Jaguar Series 3 E-Type Conv
1957 Landrover 88" Station Wagon
1957 Landrover 88"
kdiqq
United States of America
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Joined: Tue May 26, 2015 3:30 pm
Location: Houston, TX

Re: Overdriving the transfer case?

Post by kdiqq »

Well, luckily 1st gear is a crawler. So after the gear change, 1st should behave something like 2nd pre-OD regear. After further investigation though, the design of the transfer case (two input gears, one output) will make this a challenge. Between my engineering experience and the gear vendor I'm working with, I think it should be doable. I just hope it ends up being economical.
1977 Austrian 710M
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MACH
Mexico
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Re: Overdriving the transfer case?

Post by MACH »

When you build it and if you make some extra kits for sale, at a reasonable price, I could buy one.

HAS ANYONE TRIED TO CHANGE THE GEAR RATIOS AT THE PORTAL GEARBOXES? I KNOW YOU WILL LOSE SOME TORQUE.
kdiqq
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Re: Overdriving the transfer case?

Post by kdiqq »

My idea is to be able to maintain all offroading (lo range) characteristics. It'd be much easier to cut different ratio gears for the portals, but that will change everything.

I sent off a few propositions to gear vendors, but nothing is concrete yet. I'm waiting on Andre to swap t-cases to get his old one. From there I can begin making sketches and doing the engineering work behind it. I will try to produce at least two kits, but it may be cost prohibitive. It will be a unique solution in that only hi range is affected, but folks may still decide it's not worth it so I don't want to get too tied up financially. I will post details as it becomes available to be, but I'm certain no progress will be made till next year.

As of now I know I can get a spare t-case from Andre and I've had a few gear vendors tell me what I want to do (after sending SDP sketches from the service manual) is possible and at least one kit will be produced.
1977 Austrian 710M
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